发表机构
Northern Arizona University; University of California Riverside（北亚利桑那大学; 加州大学河滨分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过单轴拉伸实验表征妊娠与非妊娠大鼠盆底肌的被动力学行为，发现预处理和加载速率显著影响测量结果，且大鼠与人体数据存在差异，为跨研究比较和模型校准提供了基础。
AI 中文摘要
目的：盆底肌在阴道分娩过程中会发生较大变形，然而妊娠与非妊娠盆底肌的被动拉伸行为以及测试方案的影响仍未得到充分表征。本研究评估了妊娠、加载速率、预处理和储存条件对大鼠盆底肌被动拉伸力学特性的影响。方法：对来自妊娠和非妊娠大鼠的肛提肌样本进行单轴拉伸至破坏试验，涉及多种预处理振幅、两种加载速率以及新鲜或冷冻储存条件。通过自动化区域检测方法提取峰值和过渡指标、应变能密度、趾区刚度和高应变刚度。还将大鼠的特性与数字化的人体尸体肛提肌数据进行了比较。结果：妊娠大鼠样本达到的峰值应变高于对照组，尽管差异不显著。预处理对峰值应变的影响依赖于加载速率：在0.5%应变/秒下，响应在约2%预处理应变处趋于平稳，而在1%应变/秒下，直至15%预处理应变均未出现类似的平稳现象。与人体尸体数据相比，大鼠样本达到的峰值应变显著更大，而高应变刚度更低。结论：本研究提供了妊娠与非妊娠组织被动盆底肌力学特性之间首批直接实验比较之一，同时系统评估了多个测试方案变量对测量响应的影响。区分方案依赖性变异与生物学差异，为跨研究比较和本构模型校准提供了更可重复的基础。大鼠盆底肌是研究妊娠相关适应的有用模型，但绝对力学值在向人体组织转化时应谨慎。
英文摘要
Purpose: Pelvic floor muscles undergo large deformations during vaginal delivery, yet the passive tensile behavior of pregnant and non-pregnant pelvic floor muscle and the influence of testing protocols remain incompletely characterized. This study evaluated how pregnancy, loading rate, preconditioning, and storage affect passive tensile mechanics of rat pelvic floor muscle. Methods: Levator ani samples from pregnant and non-pregnant rats were tested in uniaxial tension to failure across multiple preconditioning amplitudes, two loading rates, and fresh or frozen storage conditions. Peak and transition metrics, strain energy density, toe-region stiffness, and high-strain stiffness were extracted using automated region-detection methods. Rat properties were also compared with digitized human cadaver levator ani data. Results: Pregnant rat samples reached greater peak strains than controls, although the difference was not significant. Preconditioning affected peak strain in a loading-rate-dependent manner: responses tapered near 2% preconditioning strain at 0.5% strain/s, whereas no comparable tapering occurred through 15% at 1% strain/s. Compared with human cadaver data, rat samples reached substantially larger peak strains and lower high-strain stiffness. Conclusion: This study provides one of the first direct experimental comparisons of passive pelvic floor muscle mechanics between pregnant and non-pregnant tissue, while systematically evaluating how multiple testing-protocol variables influence the measured response. Distinguishing protocol-dependent variability from biological differences provides a more reproducible basis for cross-study comparison and constitutive model calibration. Rat pelvic floor muscle is a useful model for pregnancy-associated adaptation, but absolute mechanical values should be translated to human tissue cautiously.
